Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;

int ans = 10000;
int h, w;
vector<vector<char>> s(60, vector<char>(60, '#'));
vector<vector<int>> a(60, vector<int>(60, 10000));
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};

void search(int cnt, int x, int y){
	a[x][y] = cnt;
	if(h==x && w==y){
		ans = min(cnt,ans);
		return;
	}
	for(int dir = 0; dir < 4; ++dir){
		int nx = x + dx[dir];
		int ny = y + dy[dir];
		if(s[nx][ny] == '.' && cnt+1<a[nx][ny])
			search(cnt+1, nx, ny);
	}
}


int main(void){
	cin >> h >> w;
	int bk = 0;
	for(int i = 1; i <= h; ++i){
		for(int j = 1; j <= w; ++j){
			cin >> s[i][j];
			if(s[i][j] == '#') bk++;
		}
	}
	search(1,1,1);
	cout << (a[h][w]!=10000?h*w-bk-ans:-1) << endl;
	return 0;
}